A self-emulsifying delivery system loaded with efavirenz: The case for flax-seed oil
- Authors: Mazonde, Priveledge
- Date: 2021-10-29
- Subjects: Drug delivery systems , Linseed oil , Antiretroviral agents , HIV (Viruses) , Drug carriers (Pharmacy) , Solubility , High performance liquid chromatography , Efavirenz
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/192944 , vital:45283
- Description: The feasibility of incorporating efavirenz (EFV), an antiretroviral agent against HIV into a lipid-based self-emulsifying drug delivery system (SEDDS) containing vegetable oils was investigated. EFV has poor aqueous solubility and is classified under the Biopharmaceutical Classification System (BCS) as a class II compound with highly permeability, its aqueous solubility is less than 10 mg/ml and is defined as a practically insoluble compound with a consequent poor bioavailability of approximately 40%, and erratic dissolution behaviour. SEDDS formulations have been shown to improve the aqueous solubility and consequently the bioavailability of BCS II compounds such as EFV. EFV is a first line antiviral agent used in combination with other agents in antiretroviral therapy (ART). Among the number of NNRTIs approved for use in HIV treatment, EFV is one of the most commonly prescribed drug. Statistical methods and Design of Experiments (DoE) using Response Surface Methodology (RSM), specifically a Central Composite Design (CCD), were used to facilitate the development of a reversed-phase high performance liquid chromatographic (HPLC) method for the quantitation of EFV during formulation product and process development studies. A rapid, accurate, precise and sensitive HPLC method with ultraviolet (UV) detection was developed, optimised and validated for the in-vitro analysis of EFV in a total run time under 10 minutes for the elution of both EFV and loratidine which was used as the internal standard (IS). The method was then successfully applied to the determination of EFV in commercially available tablets. Excipient screening was undertaken using solubility studies and revealed that EFV had highest solubility in flaxseed oil in comparison to soybean, macadamia, grapeseed, sunflower and olive oils. The non-ionic Tween® 80 and Span® 20 were selected as surfactant and co-surfactant, respectively with ethanol co-solvent as they exhibited improved miscibility with co-solvent. Pre-formulation studies were undertaken to investigate the compatibility of the API with excipients and to identify a nano-emulsion region and other emulsion types using pseudoternary phase diagrams. The phase behaviour of crude cold pressed flaxseed oil with the selected non-ionic surfactants revealed an area within pseudo-ternary phase diagrams for different surfactant-mixtures formed gels/semisolid structures which can be exploited for other drug delivery strategies that require such properties. Fourier transform infrared spectroscopy (FT-IR), powder x-ray diffraction (XRD) and Raman spectroscopy were used to identify and assess the compatibility of EFV with chosen excipients. 2 A reduction in the peak intensity was observed for EFV when combined with each hydrophobic/lipid excipient evaluated revealing that there was a marked reduction in the crystallinity of the EFV. A decrease in crystallinity in comparison with the bulk API may indicate that EFV were amorphous or sequestered in a molecular dispersion and exhibited an increased solubility for the molecule. Flaxseed oil was used as the oil phase in studies for the optimization of surfactant mixtures undertaken using DoE, specifically a D-optimal mixtures design with the flaxseed oil content set at 10% m/m was performed. Solutions from the desired optimization function were produced based on desirability and five nanoemulsion formulations were produced and characterized in terms of in vitro release of efavirenz, drug loading capacity, Zeta Potential, droplet sizes and polydispersity index (PDI). Kinetically stable nanoemulsions containing 10% m/m flaxseed oil were successfully manufactured and assessed. Droplet sizes ranged between 156 and 225 nm, Zeta Potential between −24 and −41 mV and all formulations were found to be monodisperse with polydispersity indices ≤ 0.487. SEDDS formulations of EFV in nano-sized carriers were developed and optimised, in vitro drug release varied with varying amounts of ethanol in the formulation producing formulations that exhibited differently modulated drug in-vitro release profiles that may be further manipulated for better performance and therapeutic outcomes in terms of solubility and possibly bioavailability of EFV when delivered using SEDDS rather than using tablets which in turn may lead to better therapeutic outcomes for patients with HIV. , Thesis (MSc) -- Faculty of Pharmacy, Pharmacy, 2021
- Full Text:
- Authors: Mazonde, Priveledge
- Date: 2021-10-29
- Subjects: Drug delivery systems , Linseed oil , Antiretroviral agents , HIV (Viruses) , Drug carriers (Pharmacy) , Solubility , High performance liquid chromatography , Efavirenz
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/192944 , vital:45283
- Description: The feasibility of incorporating efavirenz (EFV), an antiretroviral agent against HIV into a lipid-based self-emulsifying drug delivery system (SEDDS) containing vegetable oils was investigated. EFV has poor aqueous solubility and is classified under the Biopharmaceutical Classification System (BCS) as a class II compound with highly permeability, its aqueous solubility is less than 10 mg/ml and is defined as a practically insoluble compound with a consequent poor bioavailability of approximately 40%, and erratic dissolution behaviour. SEDDS formulations have been shown to improve the aqueous solubility and consequently the bioavailability of BCS II compounds such as EFV. EFV is a first line antiviral agent used in combination with other agents in antiretroviral therapy (ART). Among the number of NNRTIs approved for use in HIV treatment, EFV is one of the most commonly prescribed drug. Statistical methods and Design of Experiments (DoE) using Response Surface Methodology (RSM), specifically a Central Composite Design (CCD), were used to facilitate the development of a reversed-phase high performance liquid chromatographic (HPLC) method for the quantitation of EFV during formulation product and process development studies. A rapid, accurate, precise and sensitive HPLC method with ultraviolet (UV) detection was developed, optimised and validated for the in-vitro analysis of EFV in a total run time under 10 minutes for the elution of both EFV and loratidine which was used as the internal standard (IS). The method was then successfully applied to the determination of EFV in commercially available tablets. Excipient screening was undertaken using solubility studies and revealed that EFV had highest solubility in flaxseed oil in comparison to soybean, macadamia, grapeseed, sunflower and olive oils. The non-ionic Tween® 80 and Span® 20 were selected as surfactant and co-surfactant, respectively with ethanol co-solvent as they exhibited improved miscibility with co-solvent. Pre-formulation studies were undertaken to investigate the compatibility of the API with excipients and to identify a nano-emulsion region and other emulsion types using pseudoternary phase diagrams. The phase behaviour of crude cold pressed flaxseed oil with the selected non-ionic surfactants revealed an area within pseudo-ternary phase diagrams for different surfactant-mixtures formed gels/semisolid structures which can be exploited for other drug delivery strategies that require such properties. Fourier transform infrared spectroscopy (FT-IR), powder x-ray diffraction (XRD) and Raman spectroscopy were used to identify and assess the compatibility of EFV with chosen excipients. 2 A reduction in the peak intensity was observed for EFV when combined with each hydrophobic/lipid excipient evaluated revealing that there was a marked reduction in the crystallinity of the EFV. A decrease in crystallinity in comparison with the bulk API may indicate that EFV were amorphous or sequestered in a molecular dispersion and exhibited an increased solubility for the molecule. Flaxseed oil was used as the oil phase in studies for the optimization of surfactant mixtures undertaken using DoE, specifically a D-optimal mixtures design with the flaxseed oil content set at 10% m/m was performed. Solutions from the desired optimization function were produced based on desirability and five nanoemulsion formulations were produced and characterized in terms of in vitro release of efavirenz, drug loading capacity, Zeta Potential, droplet sizes and polydispersity index (PDI). Kinetically stable nanoemulsions containing 10% m/m flaxseed oil were successfully manufactured and assessed. Droplet sizes ranged between 156 and 225 nm, Zeta Potential between −24 and −41 mV and all formulations were found to be monodisperse with polydispersity indices ≤ 0.487. SEDDS formulations of EFV in nano-sized carriers were developed and optimised, in vitro drug release varied with varying amounts of ethanol in the formulation producing formulations that exhibited differently modulated drug in-vitro release profiles that may be further manipulated for better performance and therapeutic outcomes in terms of solubility and possibly bioavailability of EFV when delivered using SEDDS rather than using tablets which in turn may lead to better therapeutic outcomes for patients with HIV. , Thesis (MSc) -- Faculty of Pharmacy, Pharmacy, 2021
- Full Text:
Synthesis of novel heterocyclic systems as potential inhibitors of HIV-1 enzymes
- Authors: Sekgota, Khethobole Cassius
- Date: 2020
- Subjects: Protease inhibitors , Heterocyclic compounds , HIV (Viruses) , Quinoline , Amides , Nuclear magnetic resonance , Antiretroviral agents , AIDS vaccines , Nitrobenzaldehyde , Propylphosphonic acid anhydride
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/146502 , vital:38531
- Description: This study has focussed on the application of Baylis-Hillman methodology in the development of efficient synthetic pathways to libraries of novel 3-[(N-cycloalkylbenzamido)methyl]-2-quinolones and indolizine-2-carboxamides and on an exploration of their medicinal potential. The approach to 3-[(N-cycloalkylbenzamido)methyl]-2(1H)-quinolones involved a six-step pathway comprising: Baylis-Hillman reaction of 2-nitrobenzaldehyde derivatives and methyl acrylate to afford nitro-Baylis-Hillman adducts; thermal cyclisation of the adducts to give a range of 3-(acetoxymethyl)-2(1H)-quinolones in good to excellent yields; hydrolysis of the acetates; conversion of the resulting alcohols to the 3-chloromethyl analogues; amination; and, finally, acylation to afford the target amides. Variable temperature NMR methods were used to facilitate analysis of the ¹H and ¹³C NMR spectra which were complicated by internal rotation and cycloalkyl ring-flipping effects. On the other hand, the indolizine-2-carboxamides were obtained in several steps commencing with the Baylis-Hillman reaction of pyridine-2-carboxaldehyde and methyl acrylate. Thermal cyclisation of the Baylis-Hillman adduct afforded indolizine esters, hydrolysis of which gave the corresponding acids which served as precursors to the target indolizine-2-carboxamides. The final amidation step, however, proved to be particularly challenging. Various coupling strategies were explored to access indolizine-2-carboxamides. These included the use of 2,2,2-trifluoroethyl borate which showed limited promise, but propylphosphonic acid anhydride (T3P) proved to be the most effective coupling agent, permitting the formation of 24 novel indolizine-2-carboxamides from hydrazines, aliphatic amines and a range of heterocyclic amines. A high-field NMR-based kinetic study of the mechanism of the Baylis-Hillman reaction of pyridine-4-carboxaldehyde and methyl acrylate in the presence of 3-hydroxyquinuclidine in deuterated chloroform was initiated, reaction progress being followed by the automated collection of ¹H and DEPT 135 NMR spectra over ca. 24 hours using a high-field (600 MHz) NMR instrument. The results have provided critical new insights into the mechanism. NMR analysis has also been used to elucidate the multiplicity of signals associated with rotameric equilibria observed at ambient probe temperature. Variable temperature 1D- and 2D-NMR spectra were used to facilitate the unambiguous characterisation of the 2-quinolone benzamides and some of the indolizine-2-carboxamides. The 3-[(N-cycloalkylbenzamido)methyl]-2(1H)-quinolones, together with selected precursors, and a number of the indolizine-2-carboxamides have been screened in vitro as potential HIV-1 enzyme inhibitors. A survey of the activity of the 2-quinolones against HIV-1 integrase, protease and reverse transcriptase revealed selective inhibition of HIV-1 integrase with the most active IN inhibitor, 3-[(cyclopentylamino)methyl-6-methoxy-2(1H)-quinolone 115e, producing residual enzyme activity of 40% at a concentration of 20 μM. Many of the 2-quinolones exhibited no significant cytotoxicity against HEK 293 cells at 20 μM concentrations. 3-[(N-Cyclohexylamino)methyl]-6-methoxy-2(1H)-quinolone 114e was the only compound to exhibit ant-plasmodial activity (55% pfLDH activity). The survey of indolizine-2-carboxamides also revealed encouraging inhibition against HIV-1 integrase. None of these compounds exhibited cytotoxicity at 20 μM against HEK 293 cells, while a number of them exhibited some activity against Plasmodium falciparum (3D7 strain) and Trypanosoma brucei. Selected indolizine-2-carboxamides exhibited significant anti-tubercular activity in the 7H9 CAS GLU Tx and 7H9 ADC GLU Tw media. In view of the inherent fluorescent character and biological potential of the synthesised indolizine-2-carboxamides, their photophysical properties were explored to establish their possible dual use as bio-imaging and therapeutic agents. The major absorption and corresponding emission bands, and the associated molar absorption coefficients (Ɛ) expressed in the form of log Ɛ were determined. Their high extinction coefficients, large Stokes shift and red-shifted emissions in the visible region indicate their potential for use as fluorophores.
- Full Text:
- Authors: Sekgota, Khethobole Cassius
- Date: 2020
- Subjects: Protease inhibitors , Heterocyclic compounds , HIV (Viruses) , Quinoline , Amides , Nuclear magnetic resonance , Antiretroviral agents , AIDS vaccines , Nitrobenzaldehyde , Propylphosphonic acid anhydride
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/146502 , vital:38531
- Description: This study has focussed on the application of Baylis-Hillman methodology in the development of efficient synthetic pathways to libraries of novel 3-[(N-cycloalkylbenzamido)methyl]-2-quinolones and indolizine-2-carboxamides and on an exploration of their medicinal potential. The approach to 3-[(N-cycloalkylbenzamido)methyl]-2(1H)-quinolones involved a six-step pathway comprising: Baylis-Hillman reaction of 2-nitrobenzaldehyde derivatives and methyl acrylate to afford nitro-Baylis-Hillman adducts; thermal cyclisation of the adducts to give a range of 3-(acetoxymethyl)-2(1H)-quinolones in good to excellent yields; hydrolysis of the acetates; conversion of the resulting alcohols to the 3-chloromethyl analogues; amination; and, finally, acylation to afford the target amides. Variable temperature NMR methods were used to facilitate analysis of the ¹H and ¹³C NMR spectra which were complicated by internal rotation and cycloalkyl ring-flipping effects. On the other hand, the indolizine-2-carboxamides were obtained in several steps commencing with the Baylis-Hillman reaction of pyridine-2-carboxaldehyde and methyl acrylate. Thermal cyclisation of the Baylis-Hillman adduct afforded indolizine esters, hydrolysis of which gave the corresponding acids which served as precursors to the target indolizine-2-carboxamides. The final amidation step, however, proved to be particularly challenging. Various coupling strategies were explored to access indolizine-2-carboxamides. These included the use of 2,2,2-trifluoroethyl borate which showed limited promise, but propylphosphonic acid anhydride (T3P) proved to be the most effective coupling agent, permitting the formation of 24 novel indolizine-2-carboxamides from hydrazines, aliphatic amines and a range of heterocyclic amines. A high-field NMR-based kinetic study of the mechanism of the Baylis-Hillman reaction of pyridine-4-carboxaldehyde and methyl acrylate in the presence of 3-hydroxyquinuclidine in deuterated chloroform was initiated, reaction progress being followed by the automated collection of ¹H and DEPT 135 NMR spectra over ca. 24 hours using a high-field (600 MHz) NMR instrument. The results have provided critical new insights into the mechanism. NMR analysis has also been used to elucidate the multiplicity of signals associated with rotameric equilibria observed at ambient probe temperature. Variable temperature 1D- and 2D-NMR spectra were used to facilitate the unambiguous characterisation of the 2-quinolone benzamides and some of the indolizine-2-carboxamides. The 3-[(N-cycloalkylbenzamido)methyl]-2(1H)-quinolones, together with selected precursors, and a number of the indolizine-2-carboxamides have been screened in vitro as potential HIV-1 enzyme inhibitors. A survey of the activity of the 2-quinolones against HIV-1 integrase, protease and reverse transcriptase revealed selective inhibition of HIV-1 integrase with the most active IN inhibitor, 3-[(cyclopentylamino)methyl-6-methoxy-2(1H)-quinolone 115e, producing residual enzyme activity of 40% at a concentration of 20 μM. Many of the 2-quinolones exhibited no significant cytotoxicity against HEK 293 cells at 20 μM concentrations. 3-[(N-Cyclohexylamino)methyl]-6-methoxy-2(1H)-quinolone 114e was the only compound to exhibit ant-plasmodial activity (55% pfLDH activity). The survey of indolizine-2-carboxamides also revealed encouraging inhibition against HIV-1 integrase. None of these compounds exhibited cytotoxicity at 20 μM against HEK 293 cells, while a number of them exhibited some activity against Plasmodium falciparum (3D7 strain) and Trypanosoma brucei. Selected indolizine-2-carboxamides exhibited significant anti-tubercular activity in the 7H9 CAS GLU Tx and 7H9 ADC GLU Tw media. In view of the inherent fluorescent character and biological potential of the synthesised indolizine-2-carboxamides, their photophysical properties were explored to establish their possible dual use as bio-imaging and therapeutic agents. The major absorption and corresponding emission bands, and the associated molar absorption coefficients (Ɛ) expressed in the form of log Ɛ were determined. Their high extinction coefficients, large Stokes shift and red-shifted emissions in the visible region indicate their potential for use as fluorophores.
- Full Text:
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